Agricola, Georgius, De re metallica, 1912/1950

Table of figures

< >
< >
page |< < of 679 > >|
    <archimedes>
      <text>
        <body>
          <chap>
            <pb pagenum="408"/>
            <p type="main">
              <s>Pyrites, when they contain not only copper, but also silver, are smelted
                <lb/>
              in the manner I described when I treated of ores of silver. </s>
              <s>But if they are
                <lb/>
              poor in silver, and if the copper which is melted out of them cannot easily be
                <lb/>
              treated, they are smelted according to the method which I last explained.</s>
            </p>
            <p type="main">
              <s>Finally, the copper schists containing bitumen or sulphur are roasted,
                <lb/>
              and then smelted with stones which easily fuse in a fire of the second order,
                <lb/>
              and are made into cakes, on the top of which the slags float. </s>
              <s>From
                <lb/>
              these cakes, usually roasted seven times and re-melted, are melted out
                <lb/>
              slags and two kinds of cakes; one kind is of copper and occupies the
                <lb/>
              bottom of the crucible, and these are sold to the proprietors of the works in
                <lb/>
              which silver is parted from copper; the other kind of cakes are usually
                <lb/>
              re-melted with primary cakes. </s>
              <s>If the schist contains but a small amount of
                <lb/>
              copper, it is burned, crushed under the stamps, washed and sieved, and
                <lb/>
              the concentrates obtained from it are melted down; from this are made
                <lb/>
              cakes from which, when roasted, copper is made. </s>
              <s>If either chrysocolla or azure,
                <lb/>
              or yellow or black earth containing copper and silver, adheres to the schist,
                <lb/>
              it is not washed, but is crushed and smelted with stones which easily
                <lb/>
              fuse in fire of the second order.</s>
            </p>
            <p type="main">
              <s>Lead ore, whether it be
                <emph type="italics"/>
              molybdaena
                <emph.end type="italics"/>
                <emph type="sup"/>
              47
                <emph.end type="sup"/>
              , pyrites, (galena?) or stone from
                <lb/>
              which it is melted, is often smelted in a special furnace, of which I have
                <lb/>
              spoken above, but no less often in the third furnace of which the tap-hole
                <lb/>
              is always open. </s>
              <s>The hearth and forehearth are made from powder containing
                <lb/>
              a small portion of iron hammer-scales; iron slag forms the principal flux
                <lb/>
              for such ores; both of these the expert smelters consider useful and to
                <lb/>
              the owner's advantage, because it is the nature of iron to attract lead. </s>
              <s>If
                <lb/>
              it is
                <emph type="italics"/>
              molybdaena
                <emph.end type="italics"/>
              or the stone from which lead is smelted, then the lead runs
                <lb/>
              down from the furnace into the forehearth, and when the slags have been
                <lb/>
              skimmed off, the lead is poured out with a ladle. </s>
              <s>If pyrites are smelted,
                <lb/>
              the first to flow from the furnace into the forehearth, as may be seen at
                <lb/>
              Goslar, is a white molten substance, injurious and noxious to silver, for it
                <lb/>
              consumes it. </s>
              <s>For this reason the slags which float on the top having been
                <lb/>
              skimmed off, this substance is poured out; or if it hardens, then it is taken
                <lb/>
              out with a hooked bar; and the walls of the furnace exude the same substance
                <emph type="sup"/>
              48
                <emph.end type="sup"/>
              .
                <lb/>
              </s>
            </p>
          </chap>
        </body>
      </text>
    </archimedes>
Impressum